About Simethicone Oral anti-foaming agent, Silicones, Antiflatulent. Mechanism of Action of Simethicone This anti-gas (anti-flatulence) medication acts in the stomach and intestines to change the surface tension of gas bubbles, enabling smaller bubbles to join together into bigger bubbles. It results elimination of gas more easily by belching or passing flatus. Indications for Simethicone 1. Abdominal pain which is due to excessive gas in the digestive tract 2. Before gastroscopy or radiography of the bowel